RESUMO
The autonomic nervous system maintains homeostasis, which is the state of balance in the body. That balance can be determined simply and noninvasively by evaluating heart rate variability (HRV). However, independently of autonomic control of the heart, HRV can be influenced by other factors, such as respiratory parameters. Little is known about the relationship between HRV and spirometric indices. In this study, our objective was to determine whether HRV correlates with spirometric indices in adults without cardiopulmonary disease, considering the main confounders (e.g., smoking and physical inactivity). In a sample of 119 asymptomatic adults (age 20-80 years), we evaluated forced vital capacity (FVC) and forced expiratory volume in 1 s (FEV1). We evaluated resting HRV indices within a 5-min window in the middle of a 10-min recording period, thereafter analyzing time and frequency domains. To evaluate daily physical activity, we instructed participants to use a triaxial accelerometer for 7 days. Physical inactivity was defined as <150 min/week of moderate to intense physical activity. We found that FVC and FEV1, respectively, correlated significantly with the following aspects of the RR interval: standard deviation of the RR intervals (r =0.31 and 0.35), low-frequency component (r =0.38 and 0.40), and Poincaré plot SD2 (r =0.34 and 0.36). Multivariate regression analysis, adjusted for age, sex, smoking, physical inactivity, and cardiovascular risk, identified the SD2 and dyslipidemia as independent predictors of FVC and FEV1 (R2=0.125 and 0.180, respectively, for both). We conclude that pulmonary function is influenced by autonomic control of cardiovascular function, independently of the main confounders.
Assuntos
Humanos , Masculino , Feminino , Adulto , Pessoa de Meia-Idade , Idoso , Idoso de 80 Anos ou mais , Frequência Cardíaca/fisiologia , Pulmão/fisiologia , Fumar/fisiopatologia , Sistema Nervoso Autônomo/fisiologia , Estudos Transversais , Dislipidemias/fisiopatologia , Volume Expiratório Forçado/fisiologia , Comportamento Sedentário , Espirometria , Capacidade Vital/fisiologiaRESUMO
The autonomic nervous system maintains homeostasis, which is the state of balance in the body. That balance can be determined simply and noninvasively by evaluating heart rate variability (HRV). However, independently of autonomic control of the heart, HRV can be influenced by other factors, such as respiratory parameters. Little is known about the relationship between HRV and spirometric indices. In this study, our objective was to determine whether HRV correlates with spirometric indices in adults without cardiopulmonary disease, considering the main confounders (e.g., smoking and physical inactivity). In a sample of 119 asymptomatic adults (age 20-80 years), we evaluated forced vital capacity (FVC) and forced expiratory volume in 1 s (FEV1). We evaluated resting HRV indices within a 5-min window in the middle of a 10-min recording period, thereafter analyzing time and frequency domains. To evaluate daily physical activity, we instructed participants to use a triaxial accelerometer for 7 days. Physical inactivity was defined as <150 min/week of moderate to intense physical activity. We found that FVC and FEV1, respectively, correlated significantly with the following aspects of the RR interval: standard deviation of the RR intervals (r =0.31 and 0.35), low-frequency component (r =0.38 and 0.40), and Poincaré plot SD2 (r =0.34 and 0.36). Multivariate regression analysis, adjusted for age, sex, smoking, physical inactivity, and cardiovascular risk, identified the SD2 and dyslipidemia as independent predictors of FVC and FEV1 (R2=0.125 and 0.180, respectively, for both). We conclude that pulmonary function is influenced by autonomic control of cardiovascular function, independently of the main confounders.
Assuntos
Frequência Cardíaca/fisiologia , Pulmão/fisiologia , Comportamento Sedentário , Fumar/fisiopatologia , Adulto , Idoso , Idoso de 80 Anos ou mais , Sistema Nervoso Autônomo/fisiologia , Fatores de Confusão Epidemiológicos , Estudos Transversais , Dislipidemias/fisiopatologia , Feminino , Volume Expiratório Forçado/fisiologia , Humanos , Masculino , Pessoa de Meia-Idade , Espirometria , Capacidade Vital/fisiologiaRESUMO
1. Following in vitro treatment with 12 microM 6-hydroxy-dopamine, 2 microM B-oestradiol, 0.1 microM propranolol and 10 microM cocaine vasa deferentia isolated from young rats (21-23 days old) showed supersensitivity to norepinephrine (NE) compared to those from adult (3 months old) rats. 2. The pA2 values for prazosin were higher in young (9.6 +/- 0.1) than in adult (8.3 +/- 0.1) rat vas deferens, with the slopes of the Schild plots not different from 1.0 (0.78 +/- 0.26 and 1.14 +/- 0.14, respectively). 3. The treatment of young rats with a single dose of testosterone abolished the supersensitivity to NE and the higher affinity for prazosin. 4. We conclude that there is a reduction of neuronal NE uptake and a decrease in the sensitivity to NE in the vas deferens as the rat matures sexually. 5. Testosterone induces a decrease in the sensitivity to NE, probably via an action on the alpha 1-adrenoceptor population and the sympathetic nerve discharge in this organ.
Assuntos
Compostos de Bário , Cloretos , Músculo Liso/efeitos dos fármacos , Norepinefrina/farmacologia , Testosterona/farmacologia , Animais , Bário/farmacologia , Carbacol/farmacologia , Cocaína/farmacologia , Estradiol/farmacologia , Técnicas In Vitro , Masculino , Contração Muscular/efeitos dos fármacos , Prazosina/farmacologia , Propranolol/farmacologia , Ratos , Ratos Wistar , Ducto Deferente/efeitos dos fármacosRESUMO
1. Three daily sessions of inescapable footshock stress of 30 min duration each increased the sensitivity of the isolated pacemaker of the rat to the chronotropic effect of isoprenaline. 2. The effect of inescapable footshock stress on the sensitivity of the isolated rat pacemaker to the chronotropic effect of isoprenaline was prevented by the daily administration of the compound RU-38486, a potent antiglucocorticoid which blocks the cytosolic receptor for corticosterone. 3. The administration of the compound RU-28362, a potent agonist of the cytosolic receptor for corticosterone, during 3 days to rats which were not submitted to footshock stress induces supersensitivity to the chronotropic effect of isoprenaline. 4. It is concluded that corticosterone plays an important role in the qualitative control of the rat pacemaker beta-adrenoceptor population during adaptation to repeated footshock stress.
Assuntos
Androstanóis/farmacologia , Relógios Biológicos/efeitos dos fármacos , Eletrochoque , Isoproterenol/farmacologia , Mifepristona/farmacologia , Receptores de Esteroides , Estresse Psicológico/fisiopatologia , Animais , Citosol/efeitos dos fármacos , Citosol/metabolismo , Relação Dose-Resposta a Droga , Frequência Cardíaca/efeitos dos fármacos , Masculino , Ratos , Ratos Wistar , Receptores de Glucocorticoides/efeitos dos fármacos , Receptores de Glucocorticoides/metabolismoRESUMO
1. The effects of aging on the responsiveness of the isolated pacemaker of the rat to the chronotropic effect of norepinephrine, isoproterenol and soterenol were studied. 2. Pacemakers isolated from senescent rats (22-24 months old) showed subsensitivity to norepinephrine, isoproterenol and soterenol, when compared with pacemakers isolated from young rats (3-4 months old). The maximum response to the partial agonist soterenol was reduced. 3. Determination of the pA2 value of metoprolol in pacemakers isolated from senescent and young rats showed that the chronotropic response is mediated by a homogeneous beta 1-adrenoceptor population. 4. Inhibition of extraneuronal uptake did not potentiate the chronotropic effect of isoproterenol in pacemakers isolated from senescent rats. Addition of cocaine shifted the concentration-effect curve for norepinephrine only 2.2-fold to the left in senescent rats. 5. It is concluded that, during aging, impairment of the extraneuronal and neuronal uptake mechanisms has an important role in the control of chronotropic responsiveness to catecholamines.
Assuntos
Agonistas Adrenérgicos beta/farmacologia , Coração/fisiologia , Envelhecimento/fisiologia , Animais , Cocaína/farmacologia , Etanolaminas/farmacologia , Coração/efeitos dos fármacos , Frequência Cardíaca/efeitos dos fármacos , Técnicas In Vitro , Isoproterenol/farmacologia , Masculino , Metoprolol/farmacologia , Norepinefrina/farmacologia , Oxidopamina/farmacologia , Fenoxibenzamina/farmacologia , Ratos , Ratos EndogâmicosRESUMO
The present study was undertaken in order to analyse the effect of swimming stress on the blood pressure response to noradrenaline (NA) in unanesthetized rats. Swimming induced a desensitization of the blood pressure response to NA which was not blocked by previous animal treatment with prazosin (0.1 mg/kg). However, rats submitted to stress showed increased sensitivity to the prazosin blocking effect. The results suggest that swimming-induced desensitization of the cardiovascular response to NA is mediated by alpha rather than beta-1 adrenoceptors.
Assuntos
Pressão Sanguínea/efeitos dos fármacos , Norepinefrina/farmacologia , Esforço Físico/fisiologia , Estresse Fisiológico/fisiopatologia , Animais , Masculino , Prazosina/farmacologia , Ratos , Ratos Endogâmicos , NataçãoRESUMO
The present study was undertaken in order to analyse the effect of swimming stress on the blood pressure response to noradrenaline (NA) in unanesthetized rats. Suwimming induced a desensitization of the blood pressure response to NA which was not blocked by previnous animal treatment with prazosin (0.1 mg/Kg). However, rats submitted to stress showed increased sensitivity to the prazosin blocking effect. The results suggest that swimming-induced desensitization of the cardiovascular response to NA is mediated by alpha rather than beta-1 adrenoceptors
Assuntos
Ratos , Animais , Masculino , Pressão Sanguínea/efeitos dos fármacos , Epinefrina/farmacologia , Esforço Físico/fisiologia , Estresse Fisiológico/fisiopatologia , Prazosina/farmacologia , Ratos WistarRESUMO
1. The effects of swim-induced stress on rat atrial norepinephrine content, plasma corticosterone level and pacemaker sensitivity to catecholamines were studied. 2. Swimming for 50 min reduced the atrial norepinephrine content and induced a long-lasting increase in the plasma corticosterone level. 3. Pacemakers isolated from swim stressed rats showed supersensitivity to the chronotropic effect of isoprenaline. Sensitivity to norepinephrine was not significantly altered. Bilateral adrenalectomy or metyrapone pretreatment prevented the development of swimming-induced supersensitivity to isoprenaline. After in vitro denervation and addition of cocaine supersensitivity to epinephrine was demonstrated. 4. It is concluded that corticosterone, at least partially, mediates the supersensitivity to isoprenaline and epinephrine in pacemaker isolated from acutely swim stressed rats.
Assuntos
Epinefrina/farmacologia , Coração/efeitos dos fármacos , Isoproterenol/farmacologia , Esforço Físico , Estresse Fisiológico/fisiopatologia , Adrenalectomia , Animais , Corticosterona/sangue , Masculino , Metirapona/farmacologia , Miocárdio/metabolismo , Norepinefrina/metabolismo , Ratos , Ratos Endogâmicos , NataçãoRESUMO
1. Repeated swimming stress (three daily sessions) resulted in an increased plasma corticosterone level and subsensitivity of the isolated rat pacemaker to noradrenaline and isoprenaline. 2. Repeated swimming stress was found to decrease the affinity of beta 1-adrenoreceptors for metoprolol. 3. Bilateral adrenalectomy performed 2 days before repeated swimming stress abolished the development of pacemaker subsensitivity to noradrenaline and isoprenaline and the decrease in beta 1-adrenoreceptors affinity for metoprolol. 4. It is concluded that adrenal corticosteroids, at least partially, mediate the swimming stress-induced subsensitivity of the isolated rat pacemaker to noradrenaline and isoprenaline.
Assuntos
Corticosterona/sangue , Sistema de Condução Cardíaco/efeitos dos fármacos , Frequência Cardíaca/efeitos dos fármacos , Isoproterenol/farmacologia , Norepinefrina/farmacologia , Estresse Fisiológico/fisiopatologia , Adrenalectomia , Animais , Masculino , Metoprolol/metabolismo , Ratos , Ratos Endogâmicos , Receptores Adrenérgicos beta/metabolismo , NataçãoRESUMO
The effects of reserpine on the sensitivity of the isolated pacemaker from rat heart to the chronotropic effect of isoprenaline and noradrenaline were studied. A single large dose of reserpine (2.5 mg kg-1) administered to rats 24 h before killing induces supersensitivity of the isolated pacemaker to isoprenaline, leaving unaltered the responsiveness of the pacemaker to noradrenaline. Reserpine at the dose of 1.0 mg kg-1 did not alter the sensitivity of the pacemaker to the catecholamines. Only the larger dose of reserpine raised the corticosterone plasma level. It is possible that a corticosterone-mediated inhibition of the extraneuronal uptake process is responsible for the supersensitivity to isoprenaline. Large doses of reserpine should not be used in experiments aimed to study cardiac sensitivity to isoprenaline or extraneuronal uptake and metabolism of the catecholamine.